I need a skimmer for a 300 gallon pond..

All the skimmers are for large ponds/ Some have a floating top ring for
water heighth. But Im looking for a small one for 300 gallon pond. Can I
make on? I have a 300 and 600 gallon pump. Any ideas? I can cut into the
preformed liner since it is above ground. The filter that I have makes
the water go around the edge so I put a hole in the liner and add water
and it pours the floating stuff out. I have the pond with a 1/2 inch
square netting over it but the darn elm tree seeds still get in. I dont
want to wait 6 weeks for them to stop blowing in. Anyone know of
anything I can build? I was thinking of the 600 gom pump on the outside
in a bucket then something at the waters edge. I can go in or outside
the pond. But I perfer out. The one they for sale are to big. Thank you